Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h, w = map(int, input().split())
s = [[0 if c == '#' else 1 for c in input()] for _ in range(h)]

directions = [(0, -1), (-1, 0), (0, 1), (1, 0)]
dist = [[-1 for _ in range(w)] for _ in range(h)]
dist[0][0] = 0
q = [(0, 0)]
for y, x in q:
    for dy, dx in directions:
        ny, nx = y + dy, x + dx
        if (ny < 0 or h <= ny) or (nx < 0 or w <= nx):
            continue
        if not s[ny][nx]:
            continue
        if dist[ny][nx] >= 0:
            continue
        dist[ny][nx] = dist[y][x] + 1
        q.append((ny, nx))

if dist[-1][-1] < 0:
    print(-1)
else:
    print(sum(sum(si) for si in s) - dist[-1][-1] - 1)